Telephone system



Jan. 6, 1942. ;w. KuscHE TELEPHONE SYSTEM Filed Sept. 16, 1939 T1 7:; 2s 25 27 ,a/

INVENTOR: WALTER KUSCHE 1 ATTORNEY.

Patented Jan. 6, 1942 UNITED STATES PATENT. "OFFICE TELEPHONE SYSTEM Walter Kusche, Berlin- Steglitz, Germany, assignor to Fides Gesellschaft fur (lie Verwaltung und Verwertung von gewerblichen Schutzrechten mit beschrankter Haftung, Berlin, Germany, a

corporation of Germany 1 Claim. (.Ql. 179-86) In distant communication systems, more particularly telephone systems, it is known to use various ringing currents, for example alternating current of difierent frequencies, for selectively ringing the individual stations connected to a. party line. Where only one source of current is used different ringing signals are given, each one of which is characteristic of a certain station. It has also already been proposed to ring individually a plurality of stations connected to a two-conductor party line by one source of current without the use of different ringing signals byconnecting the call receiving devices at each station to the party line in a manner different from that which is provided in the other stations. This is effected by applying to the party line the source of ringing current corresponding to the station to be called and permits ringing three stations separately at most. In the one station the call receiving devices are arranged in shunt with the line, in asecond station they are arranged between the -a-conductor and earth and in the third branch station they are arranged between the b-conductor and earth.

The object of this invention is to provide means whereby up to six stations may be connected to one party line and be called separately while but one source of ringing current is used.

This is attained by the use of induced current, in that in each of two stations which, by differringing current can be connected to the party line in a manner adapted for the call of a desired branch station.

It is presumed that the bells provided in the individual branch stations are not connected directly to the party line, but are inserted in local circuits which are closed by the ringing relays operable over the party line by ringing current.

The ringing relays to be operated by the ringing current are not connected in the same way to the party line at the six branch stations. At the branch stations SH and SH the ringing relays Al and A2 are connected between the conductors a and earth over resistances ml and 1122;

ently connected rectifiers, are adapted to be rung by current of a different direction, the call receiving devices are arranged in bridge across the party line or between a conductor and earth, and that in a calling station a rectifier which permits only ringing current of a direction marking the desired station to pass through, is connected to the ringing circuit completed in accordance with the connection of the induction current carrying call circuit with its associated receiving device to be operated.

Fig. 1 of the drawing shows a party line. Of the equipment of individual branch stations only the call receiving devices are shown. The distant communication apparatus, for example the telephone apparatus and the guarding arrangements which may also be necessary, in order to prevent an improper connection to the seized party line are not shown, as these devices have nothing to do with the invention. Fig. 1 further shows devices in an exchange, by means of which the induction current effecting the call of a branch station can be connected to the party line in a proper way.

Fig. 2 shows a set of keys at thebranch stations St3 and S114 the ringing relays A3 and A4 are connected between the bconductor and earth over the resistances 103 and cal, and the ringing relays A5 and A6 of the branch stations St5 and StB are shunted across both conductors a and b in series with resistances 1.05 and wt- The branch stations where the ringing relays are connected to the party line in the same manner differ from each other by the different insertion of a rectifier. The rectifiers are arranged in parallel with the ringing relays, but mayalso be connected in series with the ringing relays. From the and symbols designating the individual ringing relays it can be seen in which direction the ringing current must fiow in order to 'energise the ringing relays. Energisation takes place: of relay Al, if is applied to a: of relay A2, if is applied to a: of relay A3, if is applied to b: of relay A4, if is applied to b: of relay A5, if is applied to a and applied to b, and of relay A6, if is applied to a and is simultaneouslyapplied to b.

Of the call mechanism provided in the exchange VSt only a few contacts, a repeater Ue and a starting contact an are shown. The contacts must be controlled by relays energised in a predetermined combination by a selecting operation. The selecting operation may be carried through by an operator in the exchange or by a by means of which ternating current is applied to the primary of the transformer Ue. The call circuit is completed as follows: contacts H15, 471, secondary winding of transformer Ue, contact 2r], rectifier GIII, contact 11'3, a-conductor, branch station Stl, resistance wl, relay Al, At the same time the call current at the branch station St2 passes over resistance m2 and rectifier S2 to earth. The relay A2 of the branch station St2 is short-circuited over the rectifier S2. Therefore only the relay Al of the branch station St! is operated, so that the bell WI is connected up at the contact al.

In order to call the branch station StZ the T2 contacts must be operated. Rectifier GIV will then be included in the following call circuit: earth, contacts I H5, 6T2, 3rl secondary of trans former Ue, contacts ITI, 512, rectifier GIV, contact 9T4, a-conductor, branch station S152, resistance 102, relay A2, earth. Relay A2 operates and connects up the bell W2. When negative potential is connected to the a-conductor, relay Al is short-circuited over the rectifier SI.

When the branch station S153 is to be called, the contacts TI and r3 are operated, whereby the rectifier GIII is included in the following call circuit: earth, contacts T5, 424, secondary of transformer Ue, contact 211, rectifier GIII, contacts 8T3, b-conductor, resistance w3, relay A3, earth. The bell W3 is connected up. The relay A4 of the branch station S154 is short-circuited over the rectifier S4, as positive potential is applied to the b-conductor.

In order to call the branch station St4 the contacts 1'2 and T4 are operated, so that th following call circuit is completed: earth, contacts I I15,

6T2, 3r], secondary of transformer Ue, contacts lrl, 5T2, rectifier GIV, contact HIM, b-conductor,

resistance W4, relay A4, earth. The bell W4 is connected up. Relay A3 is short-circuited over the rectifier S3.

When the branch station S735 is to be called the contacts H and T5 are caused to operate whereby the rectifier GIII is included in the following circuit: secondary of transformer Ue, contact 211, rectifier GIII, contact 113, a-conductor, resistance 2125, relay A5, b-conductor, contacts l2r5, 4H, secondary of transformer U6. The bell W5 is connected up. With this direction of flow of ringing current, relay A6 which, as relay A5, is in bridge across the line is short-circuited over the rectifier S6. When the branch station StB is to be called the contacts T2 and 1'5 are operated whereby the rectifier GIV is included in the following circuit: secondary of transformer Ue, contacts l'ri, rectifier GIV, contact 974, a-conductor, resistance wt, relay AB, Ii -conductor, contacts i2r5, 6T2, 3H, secondary of transformer Ue. The bell W6 is connected up at contact a6. Relay A5 of branch station S155 is short-circuited over the rectifier S5, as negative potential is applied to a-conductor and positive potential to the bconductor. 7

Fig. 2 shows a set of keys which may be used at the operators position in the exchange for calling a subscriber of a party line and which may also be used in each branch station for the direct call of the other branch stations of their own party line. For the mutual direct call of the branch stations inductive current must be available in the same. This current may be taken contact 40 is closed, whereby the alternating current (from a main or an inductor) is applied to the primary of the transformer Ue. Depending on which one of the keys l6 is closed the ringing current is applied to the a-conductor, or to the b-conductor, or in bridge across the line, and depending on whether the rectifier GI or the rectifier GII is inserted, only the positive or only the negative half waves of the induced current can pass into the line.

For calling the branch station Stl key TI is depressed whereby the ringing circuit is applied to the a-conductor over the following path: earth, contacts 23Tl, 35T5, 38T6, secondary of the transformer Ue, contact 22TI, rectifier GI, which permits only the positive half waves to pass through, contact 28T3, a-conductor.

When the key T2 is depressed, in order to call the branch station StZ, the induced current is likewise applied to the a-conductor, but it is applied over the rectifier GII which permits only the negative half Waves to pass through: earth, contacts 25T2, 35T5, 38T6, secondary of transformer Ue, contacts 2 VII, 24T2, rectifier GII, contact 32T4, a-conductor.

In order to call branch station St3 the key T3 is actuated. The induced current is applied to the b-conductor over: earth, contacts 21T3, 35T5, SETS, secondary of the transformer Ue, contact 26T3, rectifier GI, contact 29T3, b-conductor.

In order to call branch station S134 the key T4 is actuated. The induced current is then likewise applied to the b-conductor over earth, contacts 3lT4, 3515, 38TH, secondary of transformer Ue, contacts 2iTl, 30T4, rectifier GII, contact 33T4, b-conductor.

In the branch stations St5 and StB the call receiving apparatus is arranged in bridge across the line. Therefore, when the keys T5 or T6 are actuated, the secondary of the transformer, in series with one of the rectifiers, is also connected in bridge between the conductors a and b. When the key T5 is actuated, the rectifier GI is inserted over: b-conductor, contacts 36T5, 38T6, secondary of transformer Ue, contact 34T5, rectifier GI, contact 28T3, a-conductor. When the key T6 is depressed, the rectifier GII is inserted over: b -conductor, contact 33T6, secondary of transformer Ue, contacts ZITI, 31'1'6, rectifier GII, contact 32T4, a-conductor.

I claim:

In a party line signalling system, a line having a plurality of substations thereon, each substation having a signalling device connected either to one side of the line or the other or across the conductors thereof, rectifiers connected to each device to render each device responsive to only one polarity of signalling current, a signalling arrangement for selectively operating said devices, said arrangement comprising a source of alternating current and a pair of rectifier-s, and means including a plurality of contacts operated in combinations to connect said source through one or the other of said rectifiers either to one or the other side of said line or across the conductors thereof to operate the devices of said substations selectively by direct current of a particular polarity.

WALTER KUSCHE. 

